FIGS. 1A, 1B, and 1C illustrate the configuration of an optoelectrical connector which is disclosed in Japanese Patent Application Laid Open No. 2010-50092, as a prior art example of such kind of optoelectrical connector, which is composed of a plug and a receptacle. FIG. 1A illustrates a plug and FIG. 1B illustrates a plug which is partially disassembled. FIG. 1C illustrates a receptacle.
A plug 10 includes an insulation body 11, plug terminals which are mounted on the insulation body 11, and a metallic shell 12. The insulation body 11 includes a base part 13 which has a fitting surface 13a and a tongue piece 14 which is extended forward from the base part 13. On the base part 13, through holes in which optical fibers are housed are formed, and lenses 15 are disposed so as to be respectively housed in the through holes and protruded from the fitting surface 13a. 
The metallic shell 12 is disposed so as to surround the base part 13, and an upper housing space 16 and a lower housing space 17 are formed respectively between the tongue piece 14 and a top plate of the metallic shell 12 and between the tongue piece 14 and a bottom plate of the metallic shell 12.
The plug terminals are composed of a plurality of first terminals and a plurality of second terminals. First terminals 18 are mounted on an upper surface of the tongue piece 14 so as to be exposed to the upper housing space 16. The second terminals are mounted on a lower surface of the tongue piece 14 so as to be exposed to the lower housing space 17, though the second terminals are hidden and are not shown in FIG. 1B.
A receptacle (socket) 20 includes an insulation body 21, socket terminals which are mounted on the insulation body 21, and a metallic shell 22 which covers the insulation body 21. The insulation body 21 includes a housing space 23 for housing the plug 10, a base part 24, and a first tongue piece 25 which is extended forward from the base part 24.
The socket terminals are composed of a plurality of first terminals and a plurality of second terminals. First terminals 26 are disposed on a lower surface of the first tongue piece 25. The insulation body 21 includes a second tongue piece 27 which is extended forward from the base part 24 so as to be parallel to the first tongue piece 25, and second terminals 28 are disposed on an upper surface of the second tongue piece 27.
Through holes are formed through the first tongue piece 25 and the base part 24, and lenses 29 are respectively supported by the through holes and positioned on an end part side of the first tongue piece 25. Optical fibers are housed in the through holes in a manner to correspond to rear ends of the lenses 29.
In this example, the receptacle 20 includes two stages which are an upper stage and a lower stage each of which is provided with the housing space 23, the first tongue piece 25, the second tongue piece 27, the first terminals 26, and the second terminals 28 which are described above.
In the optoelectrical connector composed of the plug 10 and the receptacle 20 described above, when the plug 10 is inserted into the receptacle 20, the first terminals 18 of the plug 10 are connected with the first terminals 26 of the receptacle 20, the second terminals of the plug 10 are connected with the second terminals 28 of the receptacle 20, and the lenses 15 of the plug 10 are inserted into the through holes, in which the lenses 29 of the receptacle 20 are positioned, so as to be opposed to the lenses 29, thus realizing optical connection (transmission of an optical signal).
As described above, in an optoelectrical connector which can perform both of optical connection and electric connection, optical connection parts and electric connection parts are positioned in the same space. Accordingly, there is a problem that metal abrasion powder which is generated by a slide of metallic terminals in electric connection easily attaches to the optical connection parts. For example, such situation can be generated that optical coupling efficiency is largely deteriorated by attachment of metal abrasion powder to a lens or the like.
Further, the optical connection part is exposed forward in the receptacle as shown in FIG. 1C, so that the optical connection part is easily cleaned. On the other hand, the optical connection part is positioned on a deep side of a space surrounded by the shell in the plug as shown in FIG. 1B, so that it is difficult to clean the optical connection part and even if metal abrasion powder attaches to the optical connection part, the metal abrasion powder cannot be easily removed.